Abstract
Acetyl-CoA carboxylase plays a central role in regulation of fatty acid biosynthesis. Animal acetyl-CoA carboxylase is composed of one kind of subunit with a molecular weight of 260,000, which contains a biotinyl prostheic group. Primary structure of chicken liver acetyl-CoA carboxylase was deduced from the nucleotide sequence of the CDNA. On the basis of the amino acid sequence localization of functional domains including biotin carboxylase, biotin carboxyl carrier protein and carboxyl transferase domains on the polypeptide chain is discussed. Proteolysis of acetyl-CoA carboxylase has been studied and cathepsin L and B were shown to be involved in the initial phase of the degradation of acetyl-CoA carboxylase in lysosomes. Palmitoyl-CoA binds tightly and reversively to acetyl-CoA carboxylase in an equimolar ratio to inhibit the enzyme, suggesting long-chain acyl-CoA is a specific and physiological inhibitor of the enzyme. Chicken liver acetyl-CoA carboxylase is regulated by phosphorylation. Possible phosphorylation sites of the enzyme are discussed.
